1. Field of the Invention:
This invention relates to a process for making a polymeric resin by the reaction of an epoxy resin with a carboxylic acid or carboxylic acid anhydride in the presence of a tetrahydrocarbyl phosphonium bicarbonate catalyst.
2. Description of the Prior Art:
It is well known in the art to produce hydroxyl-containing ethers by reacting a vicinal epoxide with a compound bearing phenolic hydroxyls in the presence of such catalysts as tertiary amines, quaternary ammonium halides, phosphonium halides and the like. See, for example: U.S. Pat. Nos. 2,216,099; 2,633,458; 2,658,855; 3,377,406; 3,477,990; 3,547,881; 3,547,885; 3,694,407; 3,738,862; 3,948,855 and 4,048,141; German Pat. DT Nos. 2,206,218 and 2,335,199. The texts, Handbook of Epoxy Resins by H. Lee and K. Neville, McGraw-Hill (1967) and Epoxy Resins Chemistry and Technology, edited by C. A. May and Y. Tanaka, Marcel Dekker, Inc. (1973), are also of interest. U.S. Pat. No. 4,266,079 and Canadian Pat. No. 893,191 are of particular interest in that they mention the use of phosphonium bicarbonate catalysts to react epoxy resins with phenols.
It is taught in U.S. Pat. No. 4,048,141 that certain other phosphonium salts promote the reaction between vicinal epoxides and phenols and/or carboxylic acids or anhydrides. However, it is also taught therein that it is not possible to predict the activity of an onium catalyst in the reaction of epoxides and carboxylic acids based on its activity in the reaction of epoxides and phenols.